** Complementary Angles**: Two angles together are said to be complementary angles if and only if their sum is 90° (Right Angles) and each angle is said to be the complement of the other angles.

For example: – 60° and 30° are complementary angles because 60° + 30° = 90°

**Angle complement to 60° is 30° (90° – 60°)**

**Angle complement to 30° is 60° (90° – 30°)**

** Supplementary Angles**: Two angles together are said to be Supplementary angles if and only if their sum is 180° (Straight Angles) and each angle is said to be the supplement of the other angles.

For example: – 60° and 120° are Supplementary angles because 60° + 120° = 180°

**Angle supplement to 60° is 120° (180° – 60°)**

** Angle Supplement to 120° is 60° (120° – 60°)**

** Linear Pair Axiom**: It states that, if a ray stands on a line, then the sum of adjacent angles so formed is always 180° (Straight Angle). In other words we can say that if a ray stands on a line, the adjacent angles so formed are always supplementary angles.

(For detail information related to Adjacent Angles, please refer to link https://schoolacademy.sbicsphelp.com/adjacent-angle/)

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In the above figure, we have ∠ACB and ∠ACD are adjacent angles with common arm CA which stands on line BD and common vertex as point C. So,

**∠ACB + ∠ACD = 180°**

**Converse of Linear Pair Axiom**: It states that, if the sum of adjacent angles is 180°, then ** non-common arms** of the angles forms a

**.**

*Straight Line*In the above figure, if ∠ACB and ∠ACD are adjacent angles with common arm CA such that

∠ACB + ∠ACD = 180°

Then non-Common Arms CB and CD forms a straight line that is **ABC is a Straight Line**.

*Self Assignment:*

*If the measures of two Complementary angles are equal, then find the measure of each angle.**If the measures of two Supplementary angles are equal, then find the measure of each angle.*

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